Non-Contrast-Enhancing Tumor: A New Frontier in Glioblastoma Research

Abstract

There is a growing understanding of the prognostic importance of non-contrast-enhancing tumor in glioblastoma, and recent attempts at more aggressive management of this component using neurosurgical resection and radiosurgery have been shown to prolong survival. Optimizing these therapeutic strategies requires an understanding of the features that can distinguish non-contrast-enhancing tumor from other processes, in particular vasogenic edema; however, the limited and heterogeneous manner in which it has been defined in the literature limits clinical translation. This review covers pertinent literature on our growing understanding of non-contrast-enhancing tumor and focuses on key conventional MR imaging features for improving its delineation. Such features include subtle differences in the degree of FLAIR hyperintensity, gray matter involvement, and focal mass effect. Improved delineation of tumor from edema will facilitate more aggressive management of this component and potentially realize associated survival benefits.

Fig 1.

FLAIR imaging (A) showing edema around the CET component (B) sparing the cortex (arrowhead), producing the characteristic fingerlike appearance.

Fig 2.

FLAIR imaging (A) showing edema extending around the left lentiform nucleus. The CET component is shown in B.

Fig 3.

FLAIR imaging (A) demonstrating nCET involving the anterior right temporal cortex (asterisk), insula, and thalamus (arrowhead). A narrow window width has been used to improve conspicuity. The small CET component lies further superiorly (B, arrow).

Fig 4.

FLAIR imaging (A) showing eccentric extension of nCET across the corpus callosum, with associated expansion (arrowhead). Rounded hyperintensity in the left thalamus (arrow) is also consistent with nCET. Note the paucity of edema in the white matter immediately adjacent to the CET component (B).